In the Designer:

1. Insert a QML Image
2. Set it's source from, say: "assets/photo.png"
3. Run
4. Fail (it wont load and say it's not found)
...
Optional: user is perplexed because it works in the designer

This happens because you selected a file, and it truly loaded it, but in fact, at runtime, the Image is expecting it to be *inside* the QRC.

Possible Solutions:

a) Pull the file into to the QRC automatically ( maybe not a good idea, see QTCREATORBUG-12226 )
b) Eliminate loading from filesystem and force the user to fill the QRC library by hand (maybe not desirable).
c) Make QRC-everything not default as this breaks the filesystem paradigm and is, in fact, a strong usability bug.